Simply, yes.
If this is a one off purchase that you'd don't intend to replace for a few years the hot e6s is a safe purchase. If you're likely to buy next year's iPhone as well, then it might be worth sticking with what you have. Then again...
The S lines of iPhones are the ones that keep compatibility with the current iOS. iPhone 5S is still a current phone thanks to having Touch ID. It doesn't matter that it's the first generation Touch ID sensor, what matters is that it has one. It's also a 64-bit chip inside, keeping it up to date with the current processors. The resolution of the display is still being supported today, thanks to Split View and Auto Layout. The hardware is still supported, because it lacks nothing that today's iPhones have.
The 6s changes that with 3D Touch. Apples smallest device, the Watch, has a version of it, all the newest MacBook's have a Force Touch (forget the Air, the new MacBook replaces that) trackpad and it is destined to be in the iPad, Magic Trackpad and everywhere else with the next revision. Apple doesn't mess around when they say that 3D Touch is as important as multitouch. The 6s has at least another four years of software updates ahead, and the move to 2GB of RAM is another signpost. Apple is establishing a hardware baseline in their current gen products, which is 2GB of RAM for iPad Air 2, iPad mini 4 and iPhone 6s. 3D Touch is Apples big contribution in hardware, and it will be important like Touch ID has been and multitouch before that.
The history of multitouch followed much the same trajectory. First, two finger scrolling trackpads in iBooks and PowerBooks, not unlike the appearance of true multi depth multitouch in the new MacBook and then the MacBook Pro line. Then it came to the iPhone, sand then multitouch scaled to the iPad. There's no reason to think 3D Touch will be any different, moving to the iPad line with the next revision and setting a new baseline, like the 5s did with Touch ID.